The invention relates to a membrane arrangement for a pressure switch or for a pressure-responsive transmitter and to a process for connecting the membrane to a membrane supporting plate. The invention also relates to an apparatus for assembling the arrangement.
In the high-precision pressure field, for example, in gas-fired heating boilers, switching accuracies of a few Pascals are required for the monitoring of waste gases. Such accuracies can not be ensured by pressure switches of known construction. Operating pressure adjustments in the order of magnitude of less than 200 Pa or pressure differentials of less than 20 Pa are generally involved in these applications.
Pressure regulators and pressure switches for very small pressure differentials in the high-precision pressure field generally require relatively large-surface membranes offering extremely low friction resistances. Very thin membranes made from highly elastic material are especially suitable for use in high precision pressure measuring. In order to ensure the necessary stability of such membranes and to transmit the energy provided by the pressure differential to a switching or transmitter mechanism, it is commonly known to support such a membrane with a membrane supporting plate consisting of a relatively stiff material.
In order to reduce material and weight, it is advantageous to form the membrane in an annular configuration, so that it joins radially onto the membrane supporting plate without spanning the entire surface area thereof. However, the handling the storage of full-surface membrane require special care before installation. In contrast, annular membranes are substantially less sensitive, so that they can be treated harmlessly, like bulk material. As a result of such a simplification, lower production costs are obtained.
In a known arrangement, an annular membrane is fastened to a membrane supporting plate in a radially disposed groove. In this case, the membrane supporting plate is injected onto the membrane.